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I intend to use only one power supply for my project. It can supply 5A of current (though, my max load would need 1,6 so I am good whith the amount of current)

The question is what step down units are recommended so I could make 4,5 , 6, and 9V outputs.

I have no expiriance with voltage divaders so before I purchased some parts I would like to know downsides of different devices :

1-

Features:

All epoxy sealed containers with Waterproof Housing;
Light compact, convenient to use and transport;
Non-isolated
High efficiency:>96%;
Reliable, low heat dissipation max. 40 ℃;
With overload / over-current / over / low voltage protection, stable performance.
Auto recovery
Specifications:

Input range: 8~23v
Output voltage:9V
Output current/power:3A
Efficiency: >96%
Weight: 30g
Size(LxWxH): 26×36×21(mm)
Cable length: 100mm


2-

Feature:
Dimensions: length (45mm) wide (31mm) high (22mm)
Input: DC 10-15V
Ouput: DC 0.9-12V
Ouput Current:  5A
Output Power (MAX): 25W
Efficiency: 93% (12V to 5V/5A)

Testing numbers:
12V to 5V/2A:
Efficiency = (5.00 * 2.000) / (12.00 * 0.894) * 100% = 93.2%

2V to 5V/4A:
Efficiency = (5.00 * 4.000) / (12.00 * 1.782) * 100% = 93.5%

12V to 5V/6A:
Efficiency = (5.00 * 6.000) / (12.00 * 2.705) * 100% = 92.4%

12V to 5V/8A: ( A serious decline in the efficiency, Severe fever)
Efficiency = (5.00 * 8.000) / (12.00 * 3.680) * 100% = 90.6%

3-

Feature:
Input voltage: DC 7-20V
Output voltage: DC 5V
Output Current: 1A  (can work at 1A for long time)
Rated continuous current: 1A
Output power: 5W rated continuous

4-
What about this? (I guess it woun't do a job alone)


Specification:

Product Name    Positive Voltage Regulator
Model   L7812CV
VRRM   12V
IR(AV)   1.5A
Pin Length   13mm / 0.511"
Pin Spacing Pitch   2.5mm / 0.098"
Body Size   16 x 10 x 5mm / 0.6" x 0.4" x 0.2"(L * W* T)
Hole Diameter   3.6mm / 0.14"
Color   As Picture Show
Weight   4.7g

Description:

Three-terminal positive regulator are  available  in the TO-220 package and
with several fixed output voltages,  making them useful in a wide range of applications.
Output Current up to 1.5A.
Thermal Overload Protection  .                                 
Short Circuit Protection.
Output transition SOA protection.

I am sure there are plenty of other options.

I guess it's all about resistors ( pull down) which means they will use some current all the time.
That means heat too but I guess I can live with it. I use my device once a week and it's on just for a 4 hours.







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You have two main choices for DC step-down:

    Linear Regulator:  Inexpensive. Throws away excess voltage as heat.

    DC to DC Converter:  More expensive.  More efficient.

You didn't say what the input voltage is (your 5A supply).  You didn't say what the power requirement on the three output lines (4.5V, 6V and 9V) are.  You did say 1.6A but is that one EACH or all combined?
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You have two main choices for DC step-down:

    Linear Regulator:  Inexpensive. Throws away excess voltage as heat.

    DC to DC Converter:  More expensive.  More efficient.

You didn't say what the input voltage is (your 5A supply).  You didn't say what the power requirement on the three output lines (4.5V, 6V and 9V) are.  You did say 1.6A but is that one EACH or all combined?

Input (primar) voltage to my adaptor is 240V AC,
I need total current of 1,6 A.
4,5V output  200 mA
6V output, 350 mA
2 pcs 9V Outputs 400 mA each.  (total 0,8A)
I hope I could still use 12V output where I need 250 mA.

Would it be posible to isolate those two 9V outputs?

I am running two guitar effects on each output (today I use two seperate 9V adaptors )
One pair of pedals is connected to front of guitar amplifier, the other pair is connected in amplifiers LOOP (ie in between preamp and power amp).
It get noisy when I run everything on the same power supply.

 






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Here's a thought - Use a 12V (switching) supply from the wall, then provide separate linear regulators on-board for each effects unit - this will help reduce power-supply coupled noise (switching supplies are noisy, hence adding a linear regulator for every load) .  However there is still a shared ground rail then - are these devices using opamps with a mid-rail synthetic audio ground though?

Or, use 9V switcher, add good supply filtering to the two 9V devices and linear regulators for the others?
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Thank you for your help guys.
I'm going to order one linear and one fixed converter and see how they behave in my circuit.
I'll monitor heating and audio noise and decide later which one is most suitable for my application.
(I guess, the cheapest one is gonna lose, but we'll see)
Anyway, the price is not really issue here since it costs nothing comparing to what I paid for my guitars and the amplifier.








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Hello, I buyed this on ebay, you can search for "adjustable step down LM2596"



10 for <15$... smiley
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Do I need an extra heating tank for it? Or maybe
there is no need for it if the current is less than 1A???
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Do I need an extra heating tank for it? Or maybe
there is no need for it if the current is less than 1A???

Yes, recommended max current is 2A, and if you add a heatsink, up to 3A smiley

I recommend you do this, if possible:
Code:
    9V -> device
    /
12V -> device
    \
    9V -> device
      \
      6V -> device
        \
        4.5V -> device

So the step down modules won't heat a lot when lowering only few volts smiley
« Last Edit: October 30, 2012, 12:07:02 pm by guix » Logged

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This is exactly what I had in my mind! Only thing I am worried about is
how to isolate those two 9V outputs.
But, I'll try it first with no isolation and see if
it gets noisy. I can always use separate 9V adaptor like I do
at the moment but it would really be great if I could use
only one power supply cable.

Thank you!
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